Multicast is served as a core of IPTV services, so the security of multicast is an important issue. From the perspective of the realization of existing broadband access devices, there is no good solution, wherein a key problem is the authentication of a multicast source. The existing technical protocol, such as a source filtering function of the IGMPV3 protocol, is not realized or supported at a user terminal device (such as STB) or a local device due to the complexity in realization, thereby allowing any multicast server to transmit a multicast stream to a terminal device, and resulting in a security potential hazard. Therefore, the existing art cannot control or cannot dynamically control the multicast source.